An engine (an internal-combustion engine) has properties such that as the temperature of intake air is lowered, the density of intake air, namely, the weight of intake air increases. Thus, it is possible to combust fuel of a large amount and to improve the engine output. In view of the above, particularly in an engine with a supercharger, an intercooler is disposed on an intake path for cooling intake air.
In this case, employing a water cooling intercooler, and disposing the intercooler at a position near intake ports by integrally mounting the intercooler at a position immediately upstream of an intake manifold is advantageous in efficiently introducing intake air of a low temperature to cylinders. For instance, Japanese Unexamined Patent Publication No. 2001-248448 (hereinafter, referred to as Patent Literature) discloses an intake air cooling device for an internal combustion engine as described above.
When an intercooler is integrally mounted at a position immediately upstream of an intake manifold, if the position of the intercooler is lower than the position of intake ports, water (condensed water) may deposit within the intercooler. When the deposited condensed water is introduced to a combustion chamber together with intake air, an accidental fire may occur. In view of the above, it is desirable to set an intercooler to a relatively high position so that condensed water is speedily introduced to a combustion chamber without depositing within the intercooler. However, there is a limit on an increase in the height of an intercooler, taking into consideration the height of a hood.
Therefore, it is appropriate to dispose an intercooler at a position immediately outside an intake manifold on the side opposite to a cylinder head, as far as the intercooler is not lower than intake ports. However, an intake manifold is fastened to a surface of a cylinder head by bolts and nuts. Therefore, when an intercooler is integrally mounted at a position immediately outside an intake manifold, the intercooler may be an obstacle, i.e. the fastening position of the intake manifold is hidden by the intercooler. This may make it difficult to perform the operation of fastening an intake manifold, and may impair the assembling performance of an engine.